I want to convert String into Integer

Question

How to Convert String into Integer

I have a String like String date is equal "2020-03-18" , I want to convert this String into int .

Answer 1

may be if you want convert string date to int :

try {
    SimpleDateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd");
    Date parsedDate = dateFormat.parse(yourDateString);
    return parsedDate.getTime();
} catch(Exception e) { //this generic but you can control another types of exception
    // look the origin of excption 
}

Answer 2

If you need to convert this String to Date:

String date="2020-03-18";  
Date date1=new SimpleDateFormat("yyyy-MM-dd").parse(date);  
System.out.println("Date: "+date1); 

From this date you have other methods that you could get data from this Date Object ex:

date.getYear()  //would reuturn 2020 - 1900 - Year
date.getMonth() // which counts from 0 to 11 - January is 0 example
date1.getDate() // would return 18

Full code:

import java.text.SimpleDateFormat;
import java.util.Date;

/**
 *
 * @author besartm
 */
public class StringToDate {
    public static void main(String[] args) {
        String date="2020-03-18";  
        Date date1;  
        try {
            date1 = new SimpleDateFormat("yyyy-MM-dd").parse(date);
            System.out.println("Date: "+date1); 
            System.out.println("Year: "+date1.getYear()); 
            System.out.println("Month: "+date1.getMonth()); 
            System.out.println("Day: "+date1.getDate()); 
        } catch (Exception ex) {

        }
    }
}

Answer 3

If you want to convert String into an int:

int num = Integer.parseInt("2018");

If you want to convert String into Date:

import java.text.SimpleDateFormat;  
import java.util.Date;
public class HelloWorld {
   public static void main(String[] args)throws Exception {  
      String date = "2020-03-18";  
      Date date1 = new SimpleDateFormat("yyyy-MM-dd").parse(date);  
      System.out.println(date1);
   }  
}  

Answer 4

I post here example you can run and try for yourself. I converted the input string to Date object and then to number of milliseconds. However int type is not large enough to hold that value, so I advise to use long.

import java.text.SimpleDateFormat;  
import java.util.Date;

public class DateToInt
{
    public static void main(String []args) throws Exception
    {
        String dateString = "2020-03-18";  
        Date dateObject = new SimpleDateFormat("yyyy-MM-dd").parse(dateString);
        System.out.println("date: " + dateObject);

        // int cannot hold that value, overflow happens
        int int_millis = (int) dateObject.getTime();

        // long type is better for that
        long long_millis = dateObject.getTime();

        System.out.println("int: " + int_millis);
        System.out.println("long: " + long_millis);
    }
}